Abstract
The coexistent state of the spin density wave (SDW) and the charge density wave (CDW) in the one-dimensional systems is studied by the mean field approximation at T=0 in various electron-filling cases. We find that the coexistent state of SDW and CDW is stabilized at all fillings except for the half-filling when the on-site and the inter-site Coulomb interactions have the values estimated for organic conductors. The ground state energies have cusp-like minima at n/4m-filling, where n and m are integers.